WISS, JANNEY, ELSTNER ASSOCIATES

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WJE Civic Center Plaza Structural Analysis Structural Analysis of Civic Center Plaza of the Flag/Fountain ■ Provide a preliminary repot, including a field site reconnaissance memo which verifies the existing structure conditions and inventory of structure characteristics - WJE will provide a preliminary memorandum after conducting our visual survey that will include a general overview of the existing conditions and characteristics of the structure. Task 2: Inventory Existing Condition ■ Identify on a map locations of the deficiencies - WJE will provide a graphic mapping the locations and type of deficiencies noted during our visual survey. We anticipate that this will be an annotated drawing or site plan with keyed information and descriptions of deficiencies observed. ■ Document all deficiencies with photographs - WJE will document existing conditions and all deficiencies noted during our visual survey with photographs. The locations of deficiencies will be noted on an annotated drawing as noted above. ■ Identify the types of deficiency in a summary report - WJE will present our findings in a summary report that will detail the types of deficiencies noted during our visual survey, including their locations and photographs of each. ■ Perform a visual test of the structural slab, including but not limited to x-ray, to identify potential problem areas - WJE will supplement our visual surveys with nondestructive evaluation techniques. These nondestructive evaluation techniques will include chain dragging and other accepted sounding methods to identify delaminations. Sounding at the underside of the concrete slabs will be limited to those areas where cracking, mineral staining, patching, or other evidence is present to indicate possible deterioration and/or delamination of the concrete surface. In addition, based on our visual assessment, selected additional techniques will be deployed and are anticipated to include ground penetrating radar (GPR), to better characterize the levels of delaminated concrete and non -visible distress. GPR will also be utilized to determine the as -built concrete reinforcement at localized areas. Specifically, GPR will be used to located embedded reinforcement steel and determine bar spacing and depth of cover. Delamination findings will be recorded on drawings provided by the City for later analysis and determination of repair quantities. The nondestructive evaluation will be conducted at localized areas throughout the garages; however, will be sufficient to provide information regarding the entire structure. ■ WJE will propose locations to make exploratory openings that will provide confirmation for the results of our visual survey and nondestructive evaluation. Exploratory openings will be performed by a qualified contractor. Samples will also be removed for limited laboratory studies to confirm characteristics of the concrete materials and to provide information to facilitate the development of repair options. Samples will be located by WJE and removed by a qualified contractor. Laboratory studies will be completed at up to 4 samples removed from the parking garage at locations identified by WJE and confirmed by the City. Samples will be sent to WJE's in-house, independent testing laboratory located in Northbrook, Illinois for petrographic and related laboratory testing. The following tests are anticipated to be completed. • Chloride Ion Testing. WJE proposes to develop chloride ion profiles through the concrete depth to ascertain the rate of chloride diffusion and hence the remaining time to corrosion initiation. (ASTM C1152) • Petrographic Examination and Testing. Petrography can include optical, infrared, and electron microscopy; and X-ray diffractometry and emission spectroscopy as required to fully WJE No. 2020,1370 1 MARCH 11, 2020 Page 8